Breaststroke is one of swimming events, it is very important to exercise the leg strength, and the technical methods of breaststroke leg actions are as follows: Drawing back the legs: no matter the distance between the double knees in the process of drawing back the legs is narrow or wide, the principle of drawing back the legs is that the legs should be drawn back to positions most conducive to kicking on the premise of reducing the head resistance as much as possible, the inner sides of shanks and the inner sides of soles should face to water after the soles are overturned, in this way, the water push area can be the maximum, and then the maximum kicking (leg swinging) efficiency can be realized. In order to achieve such a technical state, in the process of drawing back the legs, the distance between the double knees cannot be too large, and when the process of drawing back the legs is completed and the soles are overturned, the distance between the double knees must be smaller than the distance between double ankles. If the distance between the double knees is too large, the beneficial states for water on the inner sides of the shanks and the inner sides of the soles are hard to form as shown in FIG. 6, and when the process of drawing back the legs is ended and when the soles are overturned, the distance between the double knees must be smaller than the distance between double ankles. The action of drawing back the legs must be fast: the action of drawing back the legs generates resistance, so the action of drawing back the legs must be accomplished at a higher speed, but is relatively slower than the kicking (leg swinging) action. In general, after the hands are taken back, and when the double hands touch, the action of drawing back the legs is started, and all actions of drawing back the legs and swinging the legs are accomplished within the rest short hand stretching time interval.
Phase when the action of drawing back the legs is accomplished: when the action of drawing back the legs is accomplished, the double ankles are outward, the distance between the double knees must be smaller than the distance between the double ankles, the sole overturning action has been started at this time, the included angles between the thighs and the abdomen are about 120 degrees, the shanks are folded to the thighs as much as possible, the feet firmly lean against the haunch to store force (as shown in FIG. 7 and FIG. 8). In FIG. 7 and FIG. 8, the included angles between the thighs and the abdomen are about 120 degrees, and the feet firmly lean against the haunch.
Overturning the soles: the kicking effect of breaststroke greatly depends on the technology of overturning the soles. When the action of drawing back the legs is about to end, the double feet start to perform outward overturning actions: the double feet are rotated forward, the double heels are externally separated as much as possible, toes face to the left and right sides, the knee joints are slightly rotated inward, and finally the soles and the inner sides of the shanks form the most conducive (backward) water push plane (FIG. 10).
The leg swinging (kicking) action must be started when the outward overturning action of the feet is not accomplished in place, the final outward overturning water push posture is accomplished short after the action of swinging the legs is started, and the action of swinging the legs cannot be started after the water push posture of the sole overturning action is accomplished.
Swinging the legs: the leg swinging direction: the leg swinging (kicking) direction of modern breaststroke is straight down to the back rather than horizontally swinging the legs toward the two sides. The soles and the inner sides of the shanks form the maximum water push planes and directly kick to the bottom of a pool so as to generate the maximum power. In such leg swinging mode, after the leg swinging is accomplished and the double legs are merged, the haunch and the legs rise by means of the bounce to be parallel to the water level, thereby reducing the head resistance. With respect of the action of horizontally swinging the legs toward the two sides, the effect is worse, greater head resistance is generated, and the haunch and the legs are liable to sink after the actions are accomplished.
Leg swinging route: looked down vertically, the movement trajectories of the double feet are two symmetrical curves with very small radian and are close to straight lines (FIG. 9) in the leg swinging process, and the routes of swinging the legs toward the two sides look like triangles.
At present, the training of breaststroke leg strength is usually training of muscle groups involved in breaststroke leg actions, for example, haunch (gluteus maximus, gluteus medius and gluteus round muscles) and leg muscles (quadriceps femoris, biceps femoris muscle, musculus gastrocnemius and the like) are developed by squatting with weight, leapfrog, jumping steps and other auxiliary training methods, the training of“sartorius” on the inner thighs that is important in a “water clamping” action process should be singly trained by using heavy punches or elastic bands, and thus the training steps are troublesome.